text:
|Publication number
|Publication type
|Application number
|Publication date
|Feb 2, 2010
|Filing date
|May 28, 2004
|Priority date
|May 29, 2003
|Fee status
|Also published as
|Publication number
|Dmitri Brodkin, Moisey Y. Gamarnik
|Original Assignee
|Pentron Ceramics, Inc.
|Export Citation
|BiBTeX, EndNote, RefMan
|Patent Citations (30), Non-Patent Citations (29), Referenced by (57), Classifications (60), Legal Events (6)
|External Links: USPTO, USPTO Assignment, Espacenet
This application claims priority to U.S. Application No. 60/474,166 filed May 29, 2003, entitled Methods of Fabricating Dental Restorations Using Nanocrystalline Materials, which is hereby incorporated by reference.
This invention relates to nanocrystalline ceramic powders especially useful for fabricating dental restorations and methods of fabricating dental restorations using ceramic powders comprising nanoparticles.
Techniques of fabricating all-ceramic dental restorations by hand and methods using commercial high-tech systems such as CAD/CAM systems each have their limitations and target different segments of the dental laboratory market. There are two main challenges restricting widespread use of high-strength ceramic materials for cost-effective fabrication of dental restorations and both challenges are related to the sintering step of the operation. High-strength ceramic materials are crystalline materials formed from powder and require high temperatures for sintering that result in substantial shrinkage. Any technique enabling use of these materials for dental restorations should offer ways to (1) compensate for shrinkage and (2) provide a furnace capable of reaching the temperatures necessary to sinter the material to nearly full density.
A technique reportedly providing the highest strength for manually produced copings, the Vita� In-Ceram™ method (developed by VITA Zahnfabrik), has been advertised as yielding a material with flexural strength of about 500 MPa or even higher. This technique has not become popular mostly due to esthetic limitations and a tedious multi-step fabrication procedure that includes a glass infiltration step. This glass infiltration technique is one way to circumvent the above-mentioned challenges. Vita� In-Ceram™ copings are slip-cast on a gypsum die and soft-sintered with negligible shrinkage. The final glass infiltration step does not require a special furnace. The resulting product is a fully dense restoration having undergone no shrinkage. Nonetheless, the presence of a glass phase in the glass-infiltrated ceramics makes it inferior to corresponding crystalline ceramics in mechanical strength and chemical durability.
Currently available CAD/CAM systems are capable of compensating for shrinkage by milling enlarged shapes. Moreover, high-temperature isotropic sintering results in fully dense and accurate final shapes. However, CAD/CAM systems and procedures are expensive and not affordable by small labs. For example, two of the most recently developed commercial state-of-the art CAD/CAM systems, the LAVA™ system (available from 3M ESPE) and the CERCON� system (available from Dentsply/Degussa), require the purchase of a scanner, milling machine and high-temperature sintering furnace and are currently priced in the range of approximately $60,000-$180,000. Both of the aforementioned CAD/CAM systems employ soft-sintered zirconia blocks. The blocks are milled to enlarged shapes and subsequently sintered to full density. Both systems are advertised as yielding materials having a flexural strength of about 900 MPa or higher.
Glass-ceramic materials obviate the need to compensate for shrinkage and high temperature sintering. They can be hand-built on a refractory die and sintered at fairly low temperatures to assure accuracy of the final shape. One example of such a material is an OPC™ Low Wear (available from Pentron Laboratory Technologies, LLC) porcelain jacket crown (PJC). Glass-ceramic materials can also be injection molded into a refractory investment mold formed by the lost wax technique. Examples of commercially available materials used in this process include OPC� porcelain, and OPC� 3G™ porcelain, IPS Empress� porcelain and Empress 2™ porcelain. The physical mechanism underlying the high processability/formability of these glass-ceramics is the viscous flow of its glass component. The glass-ceramic materials listed above (Optec™, OPC� and OPC� 3G™, Empress� and Empress2™ materials) have from about 40% to about 60% of a glass phase which serves as a matrix in which from about 40% (e.g., Optec) to about 60% of crystals (e.g., Empress2) are embedded. These crystals are grown in-situ by crystallization heat-treatment of the parent glass. Alternatively, in a method described by Hoffman in U.S. Pat. Nos. 5,916,498, 5,849,068 and 6,126,732, in order to improve processability of the material, up to 50% glass is added to the crystalline ceramic powder. As a result, the reported flexure strength is limited to less than 600 MPa. By introducing a glass phase into the microstructure, strength is compromised to gain better processability.
Sintering of glass-ceramic powders is a relatively fast process compared to sintering of crystalline ceramic powders due to the viscous flow mechanism of the former, which is associated with higher densification rates, but the presence of the residual glass phase limits the strength of the final product. Another benefit of the viscous flow mechanism is that the glass ceramic conforms to the shape of the die during sintering without cracking. On the other hand, crystalline ceramics can be much stronger than glass ceramics, but crystalline ceramics sinter by a solid-state diffusion mechanism that is intrinsically slow creating inhomogeneous shrinkage, generating significant sintering stresses that may result in associated cracking. Liquid phase sintering induced by the addition of sintering aids greatly enhances sinterability of crystalline ceramics by promoting particle rearrangement and solution-precipitation mechanisms but such mechanisms do not achieve all the advantages of the viscous flow mechanism.
At the same time many experimental and theoretical studies reveal a decrease of the melting temperature of nanometallic particles in comparison with the melting temperature of conventional bulk metals. Its magnitude depends mostly on particle size and crystal structure as well as particle surface conditions and the host matrix environment such as the presence of impurities, level of agglomeration, coating, deposition substrate and the like. Usually, melting is associated with a pre-melting process resulting in a change in shape of the nanoparticles followed by the formation of a liquid skin on the melting nanoparticles. The liquid skin thickness increases during melting gradually consuming the solid particle core. Transmission electron microscopy studies, such as the one discussed in "Shape Transformation and Surface Melting of Cubic and Tetrahedral Platinum Nanocrystals" by Z. L. Wang, J. M. Petroski, T. C. Green and M. A. El-Sayed, J. Phys. Chem. 102, (32) 6145-6151 (1998), have established that 8 nanometer platinum nanoparticles begin to melt at about 6000 to about 650� C., which is a much lower temperature than the melting point of bulk platinum at 1769� C. At about 500� C., cubic particles change their shape to a spherical shape with surface melting occurring at about 600� C. to about 650� C. The molten layer surrounding solid cores of platinum nanocrystals is about 1 nm in thickness at 600� C. and the thickness increases with temperature as the nanoparticles continue to melt. The "melting point depression" abbreviated as MPD is a thermodynamically driven phenomenon and can be explained by a drastic increase in the surface area/volume ratio in nano-particulate materials and the corresponding increase in their specific surface energy. This leads to a size-related dependence of melting temperature that is roughly close to 1/d functionality, where d is the mean particle size, and contains surface tension coefficients, latent heat of melting and the molten skin thickness as parameters.
Table 1 presents some experimental data illustrating the difference in melting temperatures for nanoparticles and the corresponding bulk metals and semiconductors.
Melting temperatures of the selected nanomaterials
Nano-Material Melting
Bulk Melting
Melting Point
size, nm
Temperature � C.
Temperature � C.
Depression � C.
surface melting
Diameter 4.6
Length 202
Diameter 55
surface melting
Length 1000
from ends
[1] "Shape Transformation and Surface Melting of Cubic and Tetrahedral Platinum Nanocrystals," Z. L. Wang, J. M. Petroski, T. C. Green and M. A. El-Sayed, J. Phys. Chem. 102, (32), 6145-6151 (1998).
[2] "Size-Dependent Melting Temperature of Individual Nanometer-Sized Metallic Clusters," T. Castro, R. Reifenberger, E. Choi and R. P. Andres, Phys. Rev., B 42 (13), 8548-8556 (1990).
[3] "Size Controlled Synthesis of Pd Nanowires Using a Mesoporous Silica Template Via Chemical Vapor Infiltration," K-B Lee, S-M Lee, and J. Cheou, Adv. Mate., 13 (7), 517-520, (2001).
[4] "Size-Dependent Melting Properties of Small Tin Particles: Nanocalorimetric Measurement," S. L. Lai, J. Y. Guo, V. Petrova, G. Ramanath and L. H. Allen, Phys. Rev. Lett., 77 (1), 99-102, (1996).
[5] "Melting in Semiconductor Nanocrystals," A.N. Goldstein, C. M. Echer and A. P. Alivisatos, Science, 256, 1425-1427, (1992).
[6] "Melting and Welding Semiconductor Nanowires in Nanotubes," Y. Wu and P. Yang, Adv. Mater., 13 (7), 520-523, (2001).
Onset of surface melting occurs usually at temperatures even lower than the temperature at which the entire nanoparticle melts. It can be speculated that the "molten shells" of the pre-melted nanoparticles work as "a lubricant" inducing higher mobility of the particles and higher diffusion rates and hence facilitating densification at temperatures much lower than 0.6 of the melting point (Tm).
It can be further speculated that thermodynamic considerations explaining the mechanism of MPD described above should hold for ceramic nanoparticles as well. Nevertheless, the MPD effect is not very well studied in ceramics for obvious reasons—even the depressed melting point anticipated for ceramic nanoparticles will still be very high making it extremely difficult to conduct observations similar to those for metals and semiconductors described above in Table 1.
For example, the melting point (TM) for pure alumina and zirconia are 2050� C. and 2700� C., respectively, and therefore the MPD effect of the order of 0.5 TM will result in melting temperatures for nano-alumina and nano-zirconia particles of about 1025� C. and 1350� C. However, there are some indirect indications that MPD does occur in nanoceramics such as extremely low sintering temperatures for nanopowders as reported in R. A. Kimel, Aqueous Synthesis and Processing of Nanosized Yttria Tetragonally Stabilized Zirconia, Ph.D. Thesis, The Pennsylvania State University, the Graduate School, the College of Earth and Mineral Sciences, (2002) and in G. Skandan, H. Hahn, M. Roddy and W. R. Cannon, "Ultrafine-Grained Dense Monoclinic and Tetragonal Zirconia," J. Am. Ceram. Soc., vol. 77, no. 7, pp. 1706-10 (1994), which are both hereby incorporated by reference.
These studies reported onset of densification at surprisingly low temperatures of about 0.3 TM as well as a surprising and unique ability of nanoceramics to be translucent at fairly high levels of porosity.
Some studies reported extreme difficulty in sintering nanoceramics to full density due to rapid grain growth. For example, Skandan et al. (cited above) observed that grains grew 15 times the initial particle size in the case of nano-zirconia. The other major obstacle encountered with the use of nanoparticles in the fabrication of dental articles is related to difficulties in the consolidating of bulk shapes using conventional methods like powder compaction and slip-casting. It the scope of the present invention to utilize the advantages of nanoparticulate ceramics while successfully overcoming the obstacles currently hampering use of such nanoparticulates as dental ceramics.
It is desirable to provide dental ceramics having low sintering temperatures and high strengths. It would be beneficial to provide dental ceramics having sintering temperatures that are low enough to be sintered in existing dental furnaces, yet maintaining high strength and translucency. It is most desirable to provide processing techniques for dental ceramics that result in fully densified dental ceramics.
These and other objects and advantages are accomplished by the ceramic powders of the present invention which are manufactured into dental articles. The ceramic powders may include sintering agents, binders and other similar additives to aid in the processing of the ceramic powder into a dental article. The ceramic powders are comprised of nanoparticulate crystallites. The ceramic powders may be processed into the dental article using various methods including, but not limited to, injection molding, gel-casting, slip casting, or electroforming, hand forming, cad/camming and other various rapid prototyping methods. The ceramic powder may be formed into a suspension, pellet, feedstock material or a pre-sintered blank prior to forming into the dental article.
Dental articles are produced using relatively low sintering temperatures to achieve high density dental articles exhibiting strengths equal to and greater than about 700 MPa.
Features of the present invention are disclosed in the accompanying drawings, wherein similar reference characters denote similar elements throughout the several views, and wherein:
This invention provides particulate materials that can be processed into dental restorations using both the most sophisticated state-of-the art technologies such as solid free form manufacturing (SFF) methods as set forth in U.S. Pat. No. 6,322,728, and copending commonly owned U.S. patent application Ser. Nos. 09/972,351 (US 2002/00335458), 10/053,430 (US 2002/0125592) and 09/946,413 (US 2002/0064745), all of which are hereby incorporated by reference, as well as manual techniques similar to classic methods of building porcelain jacket crowns on a refractory die (e.g. OPC™ Low Wear porcelain jacket crowns made from powder or jacket crowns made using tape-cast ceramic sheets as described in U.S. Pat. No. 5,975,905, which is hereby incorporated by reference) or slip casting a ceramic slip onto a porous die/mold.
The ceramic particulate materials of the present invention have complex hierarchical architecture with three levels of structural organization: nano-, micro-, and macro-level as shown in
Examples of metallic powders useful herein include, but are not limited to Si, Al, Mg, Zr, Y, Ce, Ta and mixtures thereof. These metals are primarily chosen because they oxidize easily and form glass-forming oxides SiO2, Al2O3, MgO, ZrO2, Y2O3, CeO2 and Ta2O5 that facilitate liquid-phase formation during sintering. Most of these oxides are currently used as sintering aids or dopants in the manufacture of high-performance ceramics such as alumina, zirconia, silicon nitride and SIALON ceramics. The advantage of adding these elements in metallic rather than oxide form is that as nanophase metal particles they are extremely reactive, have high enthalpy of oxidation, i.e., generate highly localized heat upon oxidation, and provide good coupling for microwave energy.
Examples of ceramic nanocrystalline powders useful herein include, but are not limited to, oxide ceramics such as various forms and modifications of zirconia, alumina, titania, silica, magnesia, yttria, ceria and solid solutions or mixtures thereof.
The metallic powders and ceramic nanocrystalline powders of the present invention have sintering temperatures lower than about 1300� C. and preferably lower than about 1200� C. and most preferably not exceeding about 1100� C. Sintering temperatures of lower than 1300� C. are the most economical since sintering can be carried out in the most common resistance-heated furnaces having metallic heating elements. Each dental lab has at least one burn-out furnace with a maximum continuous operating temperature of at least 1100� C. and a porcelain furnace with a maximum operating temperature of about 1200� C. The essential feature of this invention is that these powders can be processed into dental restorations using both the most sophisticated state-of-the-art technologies such as Solid Free Form Manufacturing (SFF) methods, also known as Rapid Prototyping (RP), as well as manual techniques similar to classic methods of building porcelain jacket crowns on a refractory die, or jacket crowns made using tape-cast sheets or slip casting a ceramic slip on a porous mold. Examples of SFF/RP methods include stereo-lithography (SLA) and photo-stereo-lithography including Digital Light Processing (DLP) and Rapid Micro Product Development (RMPD) mask technique, selective laser sintering (SLS), ballistic particle manufacturing (BPM), fusion deposition modeling (FDM), multi-jet modeling (MJM) and three-dimensional printing (3DP).
Particle size distribution of these powders made of granules and polycrystalline particles is designed to improve handling for making restorations by hand or to optimize powder bed or feed-stock characteristics for specific SFF methods used. Engineered particulate materials of the present invention have complex hierarchical architecture with three levels of structural organization: nano-, micro-, and macro-level as shown in
On the macro-level the particulates are formed into a nearly spherical shape with a diameter from about 10 microns to about 500 microns, more preferably from about 20 to about 200 microns. These spherical particles should preferably be solid, not hollow. The size distribution of powders useful herein should be optimized for the specific forming technique. For example, for building by hand, the particle size distribution should be bimodal with the fraction of finer particles fitting in the interstitials between the fraction of coarser particles. The ratio of the mean diameter of coarser particles (Dc) to the mean diameter of finer particles (Df), DcDf, should be more than 3 and preferably more than 6, whereas the relative amount of finer particles is from about 10 wt % to about 25 wt %. An example of particle size distribution is shown in
In addition to using nanocrystalline powders to induce low sintering temperatures, sintering aids and binders/additives may be mixed with the nanocrystalline powders to further facilitate the action of capillary forces to aid in powder consolidation and sintering. Binders used herein may include any known binder used in conventional powder processing methods and may be compounds or mixtures of compounds activated by heat, light, or other types of radiation or by chemical reaction. Examples of binders/additives include, but are not limited to, polymeric binders, plasticizers, surfactants and dispersants such as polyacrylic binders, polyvinyl alcohol (PVA) binders, polyvinyl butyral binders, stearic and oleic acids, silanes, and various natural and synthetic waxes such as paraffin wax, polyethylene wax, carnauba wax, and bee's wax.
In accordance with a method herein, ceramic powder comprising nanocrystals is mixed with a metallic sintering aid comprising metallic micro- and/or macro-size particles. Other sintering aids and binders may also be added to the mixture. During mixing, the nanocrystalline powders become coated with the additives using any of the available coating/agglomeration techniques including, but not limited to, spray drying, fluidized bed agglomeration methods, dry and wet milling and mechanical alloying. In one of the preferred embodiments of the present invention, the additives comprise metallic particulates. In another embodiment, the additives comprise ceramic nanophases and/or nanocrystallites such as grain growth inhibitors. These sintering aids/additives facilitate the thermal sintering/densification process.
After mixing, the mixture is then sintered at a temperature of less than about 1300� C., preferably at a temperature of less than about 1200� C. and most preferably in the range of temperatures from about 800� C. to about 1150� C.
In yet another embodiment, microwave processing is used to densify the particulate by sintering through the absorption of microwave energy.
Processes occurring during the melting of a material comprising nanoparticles as described above are somewhat similar to the processes occurring during liquid phase sintering as described in Fundamentals of Ceramics, M. Barsoum, McGraw Hill (1997). In both cases, the defining factor is the presence of liquid and therefore the entire process is controlled by capillary forces. In contrast however, during liquid phase sintering the liquid phase is formed due to the addition of sintering aids, and during the sintering of nanoparticles, formation of the liquid skin on nanoparticles occurs by the mechanism of surface melting, intrinsic to nanophase materials. This invention takes advantage of both intrinsic liquid formation (due to surface melting of nanoparticles) and extrinsic liquid formation (due to sintering aids). The nanocrystalline structure of the polycrystalline particles are combined with sintering aids when they are agglomerated into granules. The granules themselves are coated with a coating comprising sintering aids and agents to aid capillary forces during sintering as well as in the forming of the shape. For example, handling of the powder/liquid paste-like mixture for manual wet-condensing of ceramic powder on a refractory die is primarily controlled by capillary forces.
Particulate material comprised of nanoparticles may behave in ways similar to glass-ceramic material due to a very significant fraction of relatively disordered material on grain boundaries. In addition, extremely high specific surface energy associated with nanoparticles greatly increases the driving force for densification. A high fraction of grain boundaries substantially alters sintering behavior of nano-sized ceramics compared to that of conventional micron-sized ceramics. Surface melting of nanoparticles, resulting in liquid skin formation around nanoparticles, induces and promotes the mechanisms of sintering previously associated with liquid phase sintering such as particle rearrangement and solution-precipitation. At the same time, grain-boundary diffusion sintering mechanisms are greatly enhanced due to the enormous surface area of the nanoparticles. Normally, the presence of agglomerates inhibits densification during solid-state sintering, however, with added mechanisms of liquid phase sintering and surface melting of nanoparticles, deliberate granulation of powder is an essential feature of this invention that facilitates beneficial capillary effects during green shape fabrication and sintering.
It is expected that hand-built restorations will have some residual porosity after final sintering, however, the architecture of the powder is designed to minimize this residual porosity and spatially coordinate it to minimize its adverse effect on mechanical properties. It is now recognized that porosity is practically an unavoidable element of microstructure and porous ceramics are not necessarily weak, as stated in "Fracture Energy of an Aligned Porous Silicon Nitride," by Y. Inagaki, T. Ohji, S. Kanzaki and Y. Shigekaki, J. Am. Ceram. Soc., 83 (7), 1807-1809, (2000). Porosity as an engineered element of the microstructure of the materials of the present invention can be controlled and spatially organized through engineered hierarchy of the starting particulate material. It is well known in the art that the critical flaw size causing brittle fracture of ceramics often scales with the particle size of the starting powder. In materials of the present invention, the powder is preferably spherical in shape promoting better flowability of the powder. In the powder herein, the pore size scales with the diameter of interstitial sites formed between the particles of the powder providing that the powder was carefully condensed or compacted and attained the maximum green density of the compact. The pore size and spatial distribution will be defined by the size and spatial distribution of interstitials between the particles. For example, for a spherical powder with particle size distribution shown in curve 1 of
The equation σ=KIC/(Ya1/2) calculates the strength based on the value of fracture toughness and the critical flaw size, where
For a yttria-stabilized tetragonal zirconia polycrystals (YTZP) material with KIC of 6-9 MPa�m1/2, and a geometric factor (Y) of 2, strength will most likely be well in excess of 700 MPa.
Largest Pore Size,
KIC, MPa � m1/2
Strength, MPa
Nanocrystalline particulate ceramic materials of this invention are supplied as free-flowing powder, pre-sintered blanks, feed-stock (for injection molding) and suspensions for slip-casting or electroforming and using fabrication techniques described below to provide materials with flexure strength of at least 700 MPa and exceeding 1 GPa which is more than enough even for multi-unit posterior restorations and cantilever bridges.
The following examples illustrate the invention.
Commercially available TZ-3Y-E (which is a yttria-stabilized tetragonal zirconia powder) powder manufactured by TOSOH Corporation (Japan) with a crystallite size of about 30 nm can be sintered to full density at temperatures as low as 1350� C., which is 150� C. lower than the sintering temperature for conventional yttria-stabilized tetragonal zirconia polycrystals (YTZP) powder. Onset of sintering normally occurs at about 0.6 of the melting point (Tm) and the MPD effect described above results in a corresponding decrease in sintering temperature for nanopowder compared to conventional micron-size ceramic. If the size of the crystallites is reduced three times to about 10 nm, the anticipated reduction in the sintering temperature will be about 450� C., i.e., YTZP powder comprised of 10 nm nanoparticles is sinterable at about 1050� C. Thus, this powder may be sintered in a regular burn-out furnace with the maximum operating temperature of 1100� C. Example 2 below further illustrates the viability of sintering nanosized zirconia powders to nearly full density at temperatures lower than 1300� C. and preferably lower than 1100� C.
Two commercially available nano-sized 3 mol % yttria stabilized zirconia powders were obtained from NanoProducts Corporation (Longmont, Colo. 80504, USA). The physical characteristics of these powders are listed in Table 3. Also listed are the properties of TZ-3YS-E powder available from Tosoh Corporation (Tokyo, Japan), a conventional so-called "easy sintering" 3 mol % yttria-stabilized tetragonal zirconia powder that was used for baseline comparison. The nano-powders were mixed with 5-10 wt. % PVA binder (Elvanol 50-42, Dupont) with a mortar and pestle, and then sieved through an 80 mesh screen resulting in free-flowing, pressable powder. The conventional zirconia powder was pressable to begin with, as it contained binder.
The powders were pressed into pellets using a double action die and then vacuum bagged and cold isostatically pressed (CIPed) at 400 MPa to remove any green density gradients. The resulting pellets were approximately 3 grams in weight and measured about 12 mm in diameter and about 7 mm in height. The green density of conventional and nanosized zirconia pellets were approximately the same, 54�0.2% and 52.6�1.2%, respectively. The pellets were then burned out by heating at a rate of 2� C./m to 700� C. and holding for 2 hours. The pellets were subsequently sintered at 1200-1300� C. for 2 hours with a heating and cooling rate of 4� C./m. Density of the sintered pellets was measured by the Archimedes method using water as the immersion medium. The percent theoretical density was calculated using a theoretical density value of 6.05 g/cm3. These results are shown in
Particle Size
Specific Surface
Size (nm)
Area (m2/g)
NP-1; NanoProducts Corp.
(Longmont, CO, USA)
product number ZR3N3063
NP-2; NanoProducts Corp.
(Longmont, CO, USA)
product number ZR3N3269
Conventional 3Y-Zirconia;
7 � 2
Tosoh product TZ-3Y5-E
Example 3 further illustrates that some of these nanopowders can be sintered isotropically using simplified cup shape geometry.
Using the methods described in example 1, green cylindrical shaped bodies with dimensions of ˜12 mm diameter by ˜12 mm height were formed out of the NP-2 and conventional zirconia powders. A 5 mm diameter�8 mm deep hole was machined into the green bodies yielding a "cup" geometry. This geometry was chosen since it simulated a dental coping. After recording the orthogonal dimensions, L(x,y,z) where x and y refer to the diameters taken at a 90� rotation to each other and z refers to the height as illustrated in
Commercially available nano-sized alumina powder AL3N3197 obtained from NanoProducts Corporation (Longmont, Colo. 80504, USA) was premixed into NP-2 zirconia nano-powder used in Examples 2 and 3 above. The physical characteristics of alumina nano-powder are compared to NP-2 below:
Powders from
Corp. (Longmont,
Surface Area
Size (nm)
Size (nm)
NP-3 (product #
99.9% Al2O3
Al2O3 nano-
NP-2 (product #
94.7% ZrO2 +
YTZP nano-
The blend of 0.5 wt % of NP-3 and 99.5 wt % of NP-2 nano-powders was mixed with 5-10 wt % PVA binder (Elvanol 50-42, Dupont) with a mortar and pestle, and then sieved through an 80 mesh screen resulting in free-flowing, pressable powder. The powder was vacuum bagged and cold isostatically pressed at 400 MPa to produce green billets of about 1-2 inches in diameter and about 5-10 inches in length. Following the cold isostatically pressing step, the outer layer of the billets were removed by turning to eliminate any green density gradients that may have existed in the outer layer. The billet was further sectioned into shorter cylinders of about 30 mm in diameter and about 50-60 mm in height. The cylinders were then debinderized and pre-sintered to about 50% theoretical density in a two step firing cycle comprising heating at the rate of 1� C./minute to about 700� C. and holding for about 2 hours at this temperature followed by a 2 hour hold at about 900� C. The attained bisque densities and the anticipated Bisque-to-Final linear shrinkages were calculated for each individual block based on diameter and height measurements before and after pre-sintering.
The pre-sintered cylinders are subsequently used to mill the enlarged frameworks for dental restorations. Each framework is enlarged based on the linear shrinkage factor calculated for each individual pre-sintered cylinder from which the framework is milled. The milled frameworks are sintered at 1250� C. for 4 hours with a heating rate of 2� C./minute to densities exceeding about 95% theoretical density as determined by the Archimedes method. The isotropic shrinkage in the frameworks is confirmed by fitting frameworks on the original master model. Some of the frameworks were layered by 3G Porcelain to demonstrate the finishing steps typical in fabrication of aesthetic al-ceramic dental restoration.
The examples above demonstrate that the selected nanosized powders exhibiting sinterability below 1300� C. were consolidated into shapes that were sintered isotropically, i.e. without distortion wherein Lx=Ly=Lz=LDiameter=LHeight, where L is the linear shrinkage. It was observed that sintering of the compacts of the nanopowders capable of isotropic sintering results in nearly fully densified articles with the average grain size noticeably larger than 100 nm. Two major difficulties in processing dental articles using nanopowders were revealed: (1) the consolidation of bulk shapes by conventional methods such as powder compaction and slip-casting; and (2) sintering to achieve densities in excess of 95%.
To overcome the first processing obstacle mentioned above, solid free form manufacturing methods such as rapid prototyping or solid imaging are utilized indirectly in combination with other processing techniques such as injection molding/heat-pressing, various coating or deposition techniques such as gel casting, slip casting, slurry casting, pressure infiltration, dipping, colloidal spray deposition, direct coagulation as described in U.S. Pat. Nos. 5,667,548, 5,788,891 and 5,948,335, which are hereby incorporated by reference, and electroforming or electrophoretic deposition techniques. While SFF methods are used to fabricate enlarged substrates, dies and molds, any of the above listed techniques can be used to form nanoparticulate materials of these invention into green shapes conforming to these substrates or molds. The electroforming is a preferred method since it utilizes suspensions which are particularly beneficial for the nanomaterials herein described. Many of the nanoparticulate materials described herein are more readily obtained as well-dispersed suspensions rather than free-flowing powders. Example 5 illustrates electroforming as the preferred method of depositing ceramic nanoparticulates onto enlarged dies produced by one of solid free form manufacturing methods. Yet another preferred technique is low-pressure injection molding into negative molds of the rapid prototyped models, or alternatively existing heat pressing equipment can be used for pressing into refractory investment molds produced by lost wax technique. Example 6 illustrates low-pressure injection molding as another preferred method of forming ceramic nanoparticulates using enlarged molds produced by one of SFF methods.
To alleviate the second processing obstacle mentioned above, the nanopowders herein are agglomerated with sintering aids such as Si, Al, Mg, Zr, Y, Ce, Ta and mixtures thereof, and grain growth inhibitors such as Cr, Ti, Ni, Mn and mixtures thereof. Depending on the subsequent processing steps, these additions can be added in their elemental (metallic) form or in the form of oxides, salts, organometallic compounds, or other precursor compounds, in the form of colloids, powders and specifically nanopowders. To further lower the melting temperature, the inclusion of the above-mentioned additives as nanopowders or precursor compounds, is most preferred.
An optical scanner, ZFN D-21, available from ZFN (Zahntechnisches Fraszentrum Nord GmbH & Co. KG, Warin, Germany) is utilized to scan master models (dies) made from impressions comprising preparations for bridges and crowns. Three-dimensional CAD software provided with a ZFN D-21 scanner is used to design frameworks and copings corresponding to these master models (dies). 3D CAD files (solid models) of these frameworks and copings are enlarged using the linear shrinkage coefficient corresponding to the anticipated sintering shrinkage of the nanozirconia materials of the present invention, saved as stereolithography (.STL) files and transferred to a computer interfaced with an RP (Rapid Prototyping) machine such as Perfactory� Mini available from Envision Technologies GmbH (Marl, Germany). This machine utilizes a photostereolithography process also known as digital light processing (DLP) to build three-dimensional objects from a light curable resin. Fifteen units are built at the same time layer by layer with an individual layer thickness of about 50 microns. Individual units are separated, attached to copper wire electrodes and coated with conductive silver paint (silver lacquer) available from Gramm GmbH or Wieland Dental+Technik GmbH & Co., KG (Pforzheim/Germany). AN electroforming unit, such as AGC� Micro Plus (Wieland Dental+Technik GmbH & Co. KG), is used to deposit a dense layer of yttria-stabilized zirconia polycrystals (YTZP) from an ethanol based suspension as described in Example 3 of U.S. Pat. No. 6,059,949, which is hereby incorporated by reference. An electroforming suspension is prepared by suspending NP-2 zirconia powder available from NanoProducts Corp. (Longmont, Colo.) in pure ethanol with addition of 0.05% vol. acetyl acetone dispersant and 0.1% vol. of 5% wt. PVB (polyvinyl butyral binder) in pure ethanol. Alternatively, an ethanol-based suspension is prepared from an aqueous suspension comprising tetragonal nano-zirconia particles of about 8 nm average particle size. First, aqueous suspensions of YTZP having a crystal size of about 8 nm are prepared via precipitation from homogeneous solutions using complexation chemistry techniques. Zirconium and yttrium salts, ZrO(NO3)2.xH2O (zirconyl nitrate, Aldrich Chem., Milwaukee, Wis.) and Y(NO3)2-6H2O (yttrium nitrate hexahydrate), Aldrich Chem., Milwaukee, Wis.) are each dissolved in CO2-free deionized water in the appropriate amounts to achieve 0.5 M solutions of each. These are then mixed, in the appropriate ratio to yield the desired mol. % of Y2O3 in the final powder, with the complexing agent bicine (www.sigmaaldrich.com) (2:1 bicine:Zr (mol)). The pH of this feed solution is adjusted to about 13 by additions of TEAOH (Tetraethylammonium Hydroxide, Aldrich Chem., Milwaukee, Wis.), and the solution is then put in a teflon-lined hydrothermal vessel (Parr Instrument Company, Moline, Ill.), which is heated to 200� C. for 8 hours to hydrothermally synthesize YTZP crystals of about 8 nm in size.
Aqueous suspensions are converted into alcohol-based suspensions by centrifuging and then redispersing in ethanol. The average thickness of the electrophoretic coating is about 0.5-0.6 mm. Following electroforming of the powders onto the substrates, sintering is carried out in a Deltech furnace using a two-step firing cycle comprising heating rate of 1� C./min to about 450� C., holding at this temperature for 2 hours to remove organics, further heating at a rate of 1� C./min. to 900� C.-1100� C. and holding at this temperature for about 2 hours. Densities in excess of 90% of theoretical density can be achieved.
An optical scanner, ZFN D-21, available from ZFN (Zahntechnisches Fraszentrum Nord GmbH & Co. KG (Warin, Germany) is utilized to scan master models (dies) made from impressions comprising preparations for bridges and crowns. 3D CAD software provided with a ZFN D-21 scanner is used to design frameworks and copings corresponding to these master models (dies). 3D CAD files (solid models) of these frameworks and copings are enlarged using the linear shrinkage coefficient corresponding to the anticipated sintering shrinkage of the nanozirconia materials of the present invention, saved as stereolithography (.STL) files and transferred to a computer interfaced with an RP (Rapid Prototyping) machine such as Perfactory� Mini available from Envision Technologies GmbH (Marl, Germany). This machine utilizes photostereolithography process also known as digital light processing (DLP) to build 3D objects from a light curable resin. Fifteen units are built at the same time layer by layer with an individual layer thickness of about 50 microns. Individual units are separated and molded in a liquid silicone rubber (Silastic� M RTV Silicone Rubber from Dow Corning Corporation) which is castable and easily demolded after curing to produce negative molds for low-pressure injection molding. It should be noted that instead of using silicone negative molds, the molds for LPIM can be designed and fabricated directly using the Perfactory� Mini RP machine and the supplied software.
Feedstock containing nanosized zirconia for injection molding is prepared from a binder comprised of 75 wt % of paraffin wax (melting point of 49�-52� C.), 10 wt % of polyethylene wax (melting point of 80�-90� C.), 10% of carnauba wax (melting point of 80�-87� C.), 2 wt % of stearic acid (melting point of 75� C.) and 3 wt % of oleic acid (melting point of 16� C.) readily available from a number of suppliers. Nanosized zirconia having a crystallite size of about 19 nm and particle size of about 15 nm (available as Product Number ZR3N3269 from NanoProducts Corp., Longmont, Colo. 80504, USA) is used. The mixing is done directly in a low pressure molding (LPM) machine, (Model MIGL-33 available from Peltsman Corporation, Minneapolis, Minn.) at a temperature of 90� C. The feedstock mixture is comprised of about fifty percent (50%) by volume of a binder. Once the feed stock mixture is thoroughly mixed it is injected into the cavity of the silicone rubber molds at a pressure of approximately 0.4 MPa and a temperature of approximately 90� C. The injection-molded green part is then demolded from the silicone mold, which is done easily due to elasticity of the silicone. Green densities of approximately 50% were achieved. The green bodies were debinderized and sintered to nearly full density as described above.
Feedstock containing nanosized zirconia for injection molding is prepared from a binder comprised of paraffin wax, with minor proportions of polyethylene wax, carnauba wax, stearic and oleic acids using the same formulation as used in Example 6. Nanosized zirconia having a crystallite size of about 19 nm and a particle size of about 15 nm (available as Product Number ZR3N3269 from NanoProducts Corp., Longmont, Colo. 80504, USA) is used. The mixing is done in a KitchenAid Professional 5 mixer (St. Joseph, Mich.) in a bowl continuously heated to 90� C., which is above the melting point of the binder. Heating is achieved using a high temperature heat tape available from McMaster-Carr (New Brunswick, N.J.). The heat tape is wrapped around the mixer bowl to provide heat to the bowl. After cooling to room temperature, the resulting mix is crushed into powder to a 60 mesh (250 μm) particle size using a mortar and pestle. This powder is then ready for injection into the cavity of a mold. Additionally, the mix can be cast into pellets by pouring into a metal "clam-shell" mold, while still in the molten state.
Previously acquired stereolithography (*.STL) files of bridge frameworks and crown copings were sent to microTEC, Bismarckstrasse 142 b 47057 Duisburg, Germany) for production of the enlarged replicas using RMPD�-mask technology via toll rapid prototyping service available through microTEC's website. The replicas were fabricated in a layer thickness of twenty five microns (25 μm) from photo-curable resin.
The resulting replicas are invested in Universal™ Refractory Investment (available from Pentron� Laboratory Technologies, LLC, Wallingford, Conn.). After the investment has hardened, the resin replicas inside are eliminated by placing it into a preheated furnace thereby burning off the resin, resulting in a mold cavity for forming the dental article. The injection molding feedstock, in free-flowing granule or pellet form, as described above, is then placed into the investment mold assembly, which is then transferred into the pressing unit. It is pressed into the investment ring using an AutoPressPlus� (Pentron� Laboratory Technologies, LLC, Wallingford, Conn.) having an external alumina plunger Pressing is done at approximately 90� C., and after cooling the pressed green part is then carefully divested by sand-blasting with glass beads at a pressure of 15 psi and the plunger and mold are disposed of. Green densities of approximately 50% were achieved. The green bodies were debinderized and sintered to nearly full density as described above.
It should be noted that in all the cases described in Examples 1-7 it was observed that while the ceramic portion of the starting powder, suspension or feedstock consists of crystallites with average sizes of less than 20 nm, the sintered dental articles have average grain sizes within the range from about 100 nm to about 450 nm. It is the nature of the materials of the present invention to exhibit substantial coarsening concurrent with densification wherein the final grain size is about 10-20 times larger than the starting crystallite size.
Though not within the scope of the present invention which is directed towards sintering ceramic dental articles comprising nanopowders to nearly full density, nevertheless, it should be noted that the injection molding technology described in Examples 6 and 7 can be used to produce dental articles even if access to RP machines is not available. In the latter case, if is not possible to make enlarged replicas and green bodies fabricated therefrom as described in Examples 6 and 7, the articles will have to be presintered without shrinkage and glass infiltrated as described in U.S. Pat. Nos. 4,772,436 and 5,910,273, which are hereby incorporated by reference. In the case of YTZP zirconia cores, 3G porcelain can be used for both glass infiltration and esthetic layering of the resulting glass-infiltrated cores.
While various descriptions of the present invention are described above, it should be understood that the various features can be used singly or in any combination thereof. Therefore, this invention is not to be limited to only the specifically preferred embodiments depicted herein.
Further, it should be understood that variations and modifications within the spirit and scope of the invention may occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention. The scope of the present invention is accordingly defined as set forth in the appended claims.
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|U.S. Classification
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|International Classification
|Cooperative Classification
|European Classification
|Aug 5, 2004
Owner name: PENTRON LABORATORY TECHNOLOGIES, LLC,CONNECTICUT
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Phoenix SWAT Team Rams House, Kidnapping Suspect Shoots Himself During the Raid
The Phoenix Police Department's SWAT team rammed a house Tuesday morning with a giant truck, trying to storm the home after 32-year-old Israel Celis Sr. allegedly kidnapped his own child and beat his wife in a hotel room.
An Amber Alert that set off a nearly 12-hour chase and standoff ended Tuesday morning after Celis shot himself as police battered and swarmed the home. (The incident also prompted the Phoenix PD to post an ambiguously funny tweet trying to explain why it had driven a car into a Valley home -- read on.)
See also:
SWAT Team Called in to Track Down Woman Suspected of Shooting Cab Driver
Drug Probe Led Pima County SWAT Team to Shoot Iraq War Vet More Than 60 Times
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Regular fit
Revel in the comfort of soft fabric with this brief from Jockey. The superior fabric provides breathable comfort, while the cut offers easy leg movement. Its stylish and comfortable covered waistband gives an excellent fit on the hip.
Black brief, soft knit fabric for optimum comfort, double layered front, elasticated waistband with branding, printed branding inside for abrasion free comfort
100% combed cotton
Machine wash warm
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Eight Principles of Telecommunications Policy
Today's economy relies on information and communication moving rapidly and seamlessly across a wide variety of devices and mediums.
Overview of Initiatives 330 and 336
In this article about medical malpractice in Washington, voters will consider two ballot initiatives that deal with medical liability reform.
The Failure of Government Central Planning: Washington's Medical Certificate of Need Program
Public policy in Washington should focus on assuring access to affordable, high quality health care for all the people of our state. The Certificate of Need program fails to advan
The How-To Guide to Health Savings Accounts
A discussion about the benefits of Health Savings Accounts vs. Employer paid health care coverage, author Liv S. Finne writes;
Medical Liability Reform: A Three State Comparison
Rising medical liability insurance rates for doctors and other health care professionals has prompted the American Medical Association to label Washington a state in medical liability cri
Mandates Increase Costs and Reduce Access to Affordable Health Insurance
In this Policy Note, Paul Guppy asserts that paying for health care coverage is one of the fastest-rising costs facing businesses and families in Washington.
How Mandates Increase Costs and Reduce Access to Health Care Coverage
In this policy brief by Paul Guppy, the argument is made of the link between "raising costs facing businesses and families in Washington" as well as the heavy government regulations placed upon the
Accountability and Learning: Assessing the Seattle Families and Education Levy
Seattle school administrators are seeking approval of a fourth education levy in two years. Yet, education research shows spending more money will not improve learning for Seattle school children.
Are Unions a Benefit or Obstacle to the Education of Children?
This Policy Brief is an adaptation of a presentation Liv Finne delivered at Western Washington University's Woodring College of Education on April 20, 2011.
'Green' Schools Fail to Make the Grade: State Building Rules Do Not Raise Student Test Scores
Since the U.S. Supreme Court ruled school vouchers are constitutional in 2002, grassroots activists around the country have been organizing to support passage of school choice programs.


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Who can resist a chocolate-peanut butter combo? Here's one in an easy and fabulous cookie bar from the Bake-Off® Contest.
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RT CHICAGO(ORD) to BASEL(BSL)
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Departure through April 30. An overnight layover in Istanbul may be required. Turkish Airlines provides a free hotel stay for layovers over 10 hours.
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Woodlawn, Tennessee
From Wikipedia, the free encyclopedia
Not to be confused with Woodlawn (Nashville, Tennessee).
Woodlawn is an unincorporated community in Montgomery County, Tennessee. It is located along State Route 79 west of neighboring Clarksville. The community has a post office with the ZIP code of 37191.
It is part of the Clarksville, TN–KY Metropolitan Statistical Area.
Coordinates: 36°32′31″N 87°30′54″W / 36.542°N 87.515°W
|This Montgomery County, Tennessee geography–related article is a stub. You can help Wikipedia by expanding it.


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Lives in Pitcairn
Joined on Dec 18, 2008
email@example.com: Sounds like a good move.
(I've never heard of either of these companies)
Well I certainly do hope this results in improvements of these DR modes (DRO, ALD, HTP, ALO...) so that the results will get closer to what one can do in LR with a properly exposed raw file. Some particular suggestions:
(1) Stop underexposing the raw data just to make highlights headroom *that the instant-post-processing requires*.
(2) In raw mode, provide raw highlights blowing marks in the in-camera RGB histogram (that'd be as good as UniWB, sans the greenish preview).
(3) Implement LR-like reconstruction of partially blown highlights in-camera.
(4) Offer a few different tonemapping presets (because it is impossible to guess where the emphasis should be and what can be sacrificed in tonemapping).
Sacred: 2X TC on 400mm f/5.6 is a no-no especially on aps-c. As someone else mentioned, better results could be achieved using p&s superzoom. The only solution is longer focal length lens.
This used to be a no-no mainly because DSLR AF wouldn't work below f/5.6. Some recent better cameras have AF modules that work at f/8 (central AF point at least). For mirrorless (and LV), different restrictions apply. OSPDAF likely fails in low light even earlier, while CDAF should go lower, assuming that the image is steady.
Whether you can get a reasonable shutter time at the resulting aperture and whether the optics are good enough are separate issues.
Donald B: what is the point of a 28mm macro lens, the designer obviously has never shot macro before.
Well, there is no mainstream "wide macro". This one is as wide as it gets among regular DSLR macros, although it is in fact a normal. Mind the Laowa 15 is an off-brand non-AF exot ;)
love_them_all: Great idea. Too bad it's for the EF-M. Please make one for the Canon DSLR.
Yes you can use thin extension tubes with certain wide-angle lenses to get wide-angle macro. But the working distance may get too short for work or even negative (focus point inside the lens), and with many lenses max magnification obtainable this way is rather close-up than macro.
Is the CP-E4N Li-ion, finally?
Digitalis32: No mention of the CRI of the LEDs used, their range of illumination or any mention of the ability to control the light ratios between them. Another rushed product.
LED macro lights aren't the best choice for macro, except video, because they don't freeze motion, and proper diffusion also eats light. Proper flash with diffuser works better. But LED is likely better than nothing, well it doesn't cost much.
love_them_all: Great idea. Too bad it's for the EF-M. Please make one for the Canon DSLR.
Get the Laowa 15/4 macro. Surely possible ;)
Esign: Macro 45? Maybe, with the LEDs. Greater depth of field than with 100-200 macro lenses. I'm most concerned about distortion, because this lens could be useful as "scanner" of old drawings and other larger documents which I now have to first borrow (it's hard to persuade an archivist) and then take to the copy shop for scanning, and I have to pay $300 anyway.
> "Greater depth of field than with 100-200 macro lenses."
The difference in DoF is likely negligible. What you see is less relative background blur.
Donald B: what is the point of a 28mm macro lens, the designer obviously has never shot macro before.
Many P&S users like wide-angle macro for the low relative background blur (they think it is more DoF, though this is not the case actually). Check the Laowa 15/4 wide-angle 1:1 macro lens too. But here it certainly has sth to do with budget and compact size.
ttran88: The real question is when will an OVF ever catch up to an EVF with 425 focus points, eye AF or even WYSIWYG? These benefits far outweigh the one benefit the OVF is hanging on to by a thread.
On the other hand, I'm still looking forward to the time when it catches up with OVF sharpness, without having to zoom.
magneto shot: i thought this is news, until i selected A7ii on the right. it blew the canon like a canon ball.
"But some people are intent on "educating" others that Sony sensors are the only way."
And other people are intent on "educating" others that this issue is so overblown ;)
magneto shot: i thought this is news, until i selected A7ii on the right. it blew the canon like a canon ball.
But the Sony A6000 doesn't seem as good as the D7200?
_sem_: An interesting review of a peculiar lens.
It would be nice to see a macro (or closeup) comparison with a workaround - a wideangle prime on a short extension tube. I hear certain Canon wideangles do reach 1:1 on extension.
Some data here:
Doesn't seem to work with the 15mm. Canon's 12mm is a bit thick indeed. I've got a 6mm K1 ring for Nikon, all manual and had to shave it a little bit but works with many wideangles, including various APS-C 18-xxx zooms, AI-s 20/3.5. But none I've tried really got close to 1:1 on extension tubes (incl. thicker ones) before the working distance shrunk to nil.
Kamox: In the rare cases I need strong macro, i use an inversion ring.
Cheap and effective.
It is possible to use ultra-wides on a reversal ring, but that's useful for very strong magnifications only. This one is more valuable for wide-angle close-ups at lower magnifications (at 1:1, no light on the subject...)
An interesting review of a peculiar lens.
It would be nice to see a macro (or closeup) comparison with a workaround - a wideangle prime on a short extension tube. I hear certain Canon wideangles do reach 1:1 on extension.
Mister Roboto: Too expensive, I am using a Generic 8mm f/3.8 Fisheye lens that I bought for 60 bucks.
Not so difficult to find a fisheye which focuses down to 1 inch or so, but in most cases they can't go near 1:1 magnification.
The thinnest available extension tubes are mostly too thick for use with fisheyes and ultrawides. Many wideangles are useful on short extension for wide-angle closeups, but just a few of them get to 1:1 at a positive working distance.
2eyesee: Another APS-C body, but Sony have abandoned APS-C E-mount lens development, and announcing this camera on the same day as three FE lenses is really rubbing our noses in it.
I don't care how good the AF is if after all these years Sony still can't offer a decent kit lens. I got the A6000 when it first came out and returned it because the 16-50 kit lens was so bad. The 18-55 is no better.
Joke is, they still have a better lens lineup than canikon mirrorless
_sem_: I expected a bigger display...
You can, but that's not very convenient is it? Pity camerphones have much better screens, hehe. The flash radio transmitter is tiny but I also find it very odd that a pro camera this size and $$$$ doesn't have one inside...
I expected a bigger display...
Jim F: Last bullet point in the description of the D750 firmware update list - "Optimal vibration reduction is now available with vibration reduction lenses." I wonder just what that really means. Does that mean that there is or was a "sub-optimal" option? Curious
@iainlea point 2: Did you use MLU and exposure delay? It is well known that the mirror vibration issue actually gets worse if the camera is rigidly mounted. As for shutter vibration, that's tougher because only electronic shutter or EFCS can work around.
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The Day/Ordet
Dir. Carl Dreyer (1955). Dreyer's penultimate feature, a rural chamber drama, one of his most demanding works, explores the clash between orthodox religion and true faith. It concerns a young farmer who believes that he is Christ, and through a child's faith performs a miracle. Slowly paced, visually stunning, it remains an estimable achievement.
Sun., Jan. 17, 7 p.m., 2010
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...I'm a fluent Spanish speaker with over 10 years of experience tutoring in the language. I've studied Spanish at both the high school and college level, taking intensive international relations classes in the subject. In high school, I received a 4 on the Spanish AP exam.
21 Subjects: including Portuguese, reading, Spanish, physics
Palo Alto, CA
...I`m a self-starter and multi-tasker with enthusiasm and high-energy. Completely self-directed nature with the ability to manage time and prioritize assignments. I am a teacher of the languages: English and Portuguese, an interpreter, illustrator and a translator and Music Teacher.
10 Subjects: including Portuguese, Spanish, writing, English
San Jose, CA
...As part of my MA in French, I studied at various universities in Paris, where I worked primarily in Philosophy and Gender and Women's studies. My Master's thesis discussed the metaphor of cannibalism and violence in Montaigne, Laclos, Duras, and Césaire. I am now working towards a PhD in Romance Languages, and a chapter of my dissertation discusses Rabelais, Montaigne, and Descartes.
58 Subjects: including Portuguese, Spanish, reading, English
Oakland, CA
...I want to learn from my students as much as they want to learn from me. This is a two-way process. Luckily, I had the opportunity to work one-on-one with many students throughout my graduate school career, be it during office hours or mentorship programs, each with their own unique learning sty...
18 Subjects: including Portuguese, chemistry, calculus, physics
Walnut Creek, CA
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6 Subjects: including Portuguese, English, biology, grammar
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Separate names with a comma.
The stove is set on room temp, set at 70 degree's, feed rate of 3-1/2, okanagen Douglas fir and I'm only seeing 220 degrees on the vent right...
I'm aiming the IR gun on the vent right above the front door of each stove and only seeing temps in the low 300's. Is that normal or should I see...
Harman Accentra insert & upright pellet stoves
Oakanagen Douglas Fir pellets
can anyone tell me what temps they are getting right above both...
How much of a chore is it to replace the ignitor on a Harman Accentra Insert?
Any suggestions on a good place to buy a new ignitor?
BU**chit, Like Andy said you are better off going to Barre.
I second that....
Sounds like the same thing I went thru. Mine were put on order back in mid- August with a sched. delivery of 9/7/2012 and was told they were out...
Something has to be funky on your stove, a 15 x 15 room and you went thru 1 bag in 14 hours??
I have the Accentra insert upstairs and the Accentra free stand in the cellar. When they are set up and running properly you'll have to open...
Anyone try Maine Wood Pellets?
Good or Bad?
How did they burn?
Lots of ash ?
How was it cleaning the stove after burning these pellets?
Beer in fridge check
gas for generator check
crown royal in cabinet check
gas for grille check
freezer full of food check
Used a home dept shop vac for 2 years with a hepa filter. Bought a Love Less ash vac from a local dealer. it's a coin toss which one does a better...
HONDA - the only way to go for generators.
I am guessing 10 or less
During the winter mine only gets shut down for cleaning, other then that it is running 24/7
Season #4 started a few nights ago
Ran the stove in the cellar this weekend, kept the house right around 68
cellar stove on Saturday night after it was serviced, it may be on for a little while tonight.
As long as it is still dropping in to the 40's and 30's at night my pellet stove is not getting shut down.
Still have close to a ton sitting in the cellar but planning on ordering soon. Thinking for this coming winter I will get 2 tons of Okanagens and...
Stove is still running almost every night, think I still got another week or two until the stove gets shut down for the summer.
6 tons YIKES, we did 3 tons in to the cellar in just about a hour.
Still burning gets chilly at night, got a few more weeks of burning. I am in no rush to shut them down.
It's not too bad, only time it gets a little noisy is when the stove is due for cleaning. Once the stove is cleaned the noise level drops.
I have my tv less then 3 feet above my pellet insert, have not had any issues with the tv.
LOL Nope not in Blazing Saddles Southern Central Mass
Thanks, I will check out the link.
Any suggestions on where to buy a new hot ash vac?
I knew last weeks weather was too good to be true, the stoves were cleaned and ready for the temps to drop. Usually do not shut down the stoves...
It is pretty much free except for the cost of beer. I have the chimney brushes and all the other tools to do the cleaning, with 2 stoves it is...
Not yet, I wait until April 15th to shut down the stove for the season. It hasn't run for 2 days but it is ready to go when the temps drop.


text:
About Us
Matt Damon Posts
Jennifer Garner Looks Pregnant Even Though Reports Claim She's Not Calling Off Divorce From Ben Affleck
June 09, 2016... if you work in entertainment news, you're always on bump watch! Jennifer Garner dropped by the Brentwood Country Mart yesterday with son Samuel, and we couldn't help but notice that the actress' mid-section seemed noticeably fuller. She's super skinny and...
Maybe The Paps Should Get Their Questions Straight Before Busting Matt Damon's Balls?
September 30, 2015... Our photog tried to nail Matt Damon to the wall about his recent gaffs -- but the 44-year-old turned the tables on the paps and made us look like fools. Nice one, Matty! The actor, who has come under fire and...
Matt Damon Clarifies His Comments On Gay Actors Coming Out In The Industry
September 29, 2015... Damage control! Matt Damon caused an uproar when his words were taken out of context and it appeared he suggested that gay actors stay in the closet in an interview with The Guardian, so the actor sat down with Ellen Degeneres...
Matt Damon Dumps Toilet Water On His Head To Raise Awareness For ALS And Water Conservation
August 26, 2014... Jimmy Kimmel and Ben Affleck nominated Matt Damon for the ALS Ice Bucket Challenge, but seeing as the Oscar winner runs Water.org, he had some reservations about wasting a whole bunch of H2O. "It posed kind of a problem for me,...
Ben Affleck And Matt Damon Bond Over Lunch
March 07, 2014... This is one bromance that shows no signs of slowing down. With Ben Affleck's wife Jennifer Garner in the Big Apple on business, Ben and Matt Damon spent quality time together on Thursday. How do you like them apples? The dynamic...
Matt Damon Is On Daddy Duty At Chris Hemsworth's Baby Shower
February 24, 2014... The celebrity baby circle is about to get bigger! Matt Damon took his daughters Isabella, Gia and Stella to Chris Hemsworth and Elsa Pataky's baby shower in Los Angeles on Saturday. The Oscar-winner was on daddy duty as he accompanied his...
Matt Damon And George Clooney Promote
Monuments Men
In Milan
February 11, 2014... Could they have picked sexier actors for this movie?! Matt Damon and George Clooney walked the red carpet in Milan last night for their new film Monuments Men, and with stars this hot, we have no doubt the flick is...
Matt Damon And George Clooney Get Cheeky On Italian TV
February 10, 2014... George Clooney and Matt Damon appeared on Che Tempo Che Fa in Milan over the weekend, and as usual, the actors totally played off of each other during a panel discussion about their new film, The Monuments Men. The previous night...
Matt Damon Doesn't Let Anything Bring His Spirits Down ... Even A Broken Collarbone!
January 05, 2014... From carrying one of his daughter's hot pink backpacks to walking through Los Angeles International Airport with a sling on his arm and a smile on his face, Matt Damon is such a good sport! On Saturday night the actor jetted...
Matt Damon Says Ben Affleck Playing Batman Is "A Matter Of National Security"
August 28, 2013... It may have been 15, years since Matt Damon and Ben Affleck won the Oscar for Good WIll Hunting -- but these buds are clearly friends to the end! Matt Damon was spotted leaving LAX on Tuesday and when asked...
Check Out Matt Damon And George Clooney's New Trailer For
The Monuments Men
August 08, 2013... George Clooney and Matt Damon are together again! Check out the sexy Ocean's franchise stars in the brand-new trailer for their upcoming film, The Monuments Men. We love anything with both of those scrumptious fellas! The film, which is also directed...
Matt Damon Keeps It Casual At
The Late Show With David Letterman
August 01, 2013... Matt Damon stopped by The Late Show With David Letterman on Wednesday evening, and before slipping into a suit and tie, the 42-year-old actor posed for photos in a Boston Celtics tee. Take that, Lakers fans! Matt is currently promoting his...
Matt Damon Shows Love To His Fans At LAX
June 25, 2013... We had forgotten what Matt Damon looked like after all the transformations he's gone through for his latest film roles (see the Elysium trailer and his role as Liberace's lover in Behind the Candelabra). Matt and his wife Luciana Barroso were...
Olivia Wilde, Bono, and Richard Branson Join Matt Damon's "Toilet Strike"
May 24, 2013... Matt Damon, Olivia Wilde, Bono, and Richard Branson are trying to end the world water crisis ... one toilet at a time. As Matt said back in February when he started the movement, he and his pals "won't go to the...
Matt Damon And Wife Luciana Renew Wedding Vows In St. Lucia
April 15, 2013... It's nice to see that some Hollywood marriages really do stand the test of time! Matt Damon and wife Luciana renewed their wedding vows in an intimate island ceremony at the Sugar Beach resort in St. Lucia on Saturday,...
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iHerb Customer Reviews
Savings of: $11.83 (47% off)
Sorry, this product is no longer in stock.
mixes well
Posted by Reviewer1745533 on Sep 27, 2011
the nasty taste of bcaa is well covered up, and it mixes well. just let it sit for a few minutes and shake well.
Muscle gain support
Posted by Reviewer1382104 on Sep 18, 2012
Go hard or go home! But you need to be with this muscle support.
Good post-workout
Posted by 5134444450372759470 on Jul 15, 2013
My husband and I can tell a difference if we neglect to drink this after our workouts. This helps to avoid aches and pains that come with pushing your body. The taste could be better, but it isn't a problem if we mix it with low-calorie sports drink.
Posted by Reviewer1134692 on Apr 20, 2014
It doest mix or taste very good, but the ratio of ammino acids are good. It would of been nice if they put it in a berry flavor.
Very cost effective product.
Posted by 4975526043472947408 on Feb 22, 2015
Don't have to purchase BCAA and Glutamine separately. Totally satisfied.
Good for what it is but taste so bad
Posted by 5238205095664512854 on Aug 02, 2015
It's really a good product for what it's intended to be, although it's actually 26 servings not 30 as the page say, still good price and the fact it contains L-Glutamine increase it's value. I had no problems with how it mix with the water, but the taste is really bad with water and it will also ruin protein taste. it doesn't taste lemonade at all, but towards the end of it you kinda of get used to it. I think I will buy it again, but I just hope they either make the taste better or make new flavours or even unflavoured.
Value for money!!
Posted by 4802741011999820524 on May 03, 2016
helps the muscle recovery and you can see fast results
Posted by Reviewer2918349 on Mar 07, 2008
It is delicious.
pretty good!
Posted by Reviewer2723020 on Feb 23, 2010
lemonade flavour is not as strong as i'd like,i have had a grapeflavoured one in the past that was also sugar free but sweeter than this one, you can taste the branch chains flavour but that doesnt bother me too much, give it a try for yourself, if you want it sweeter you could alway add a splenda or other sweetener like i do occasionally
Posted by Reviewer1675495 on Jan 17, 2011
Very good product


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This star rating is the opinion of the property owner only. A Self-Rated hotel has not been assessed by the AA or Visit Britain, whose official star ratings we use across LateRooms.com.
Skaritz Hotel and Residence4 Self rated
Price FromView Rooms
- Excellent
- 3 guest reviews
"Lovely grand hotel - but boutique - very central to town. Great room which was very quiet even though facing front street...."
"Had a lovely few days in this hotel which was very well situated within the old town. Room was extremely large and spotlessly clean. Great v..."
"would definetely stay again. we just love this place...."
About the hotel
This charming hotel enjoys a city centre location in Bratislava. It lies just 40 metres from Bratislava Castle, 100 metres from the centre of the old town and 500 metres from both St. Martin's Cathedral and the Slovak National Theatre.
This beautiful boutique town hotel comprises 20 guest rooms. Fully air-conditioned, it welcomes its guests into a lobby with 24-hour reception and check-out service, hotel safe, cloakroom and lift access. There is an on-site café and restaurant, and WLAN access is available. Room and laundry services are also provided for guests' convenience. The well-equipped guest rooms and apartments come with the latest in-room amenities, including hairdryer, direct dial telephone, satellite TV, radio, stereo system, Internet access, safe, central heating and air conditioning. The rooms are en suite with bathtub/shower and may include a kitchenette with minibar and tea and coffee making facilities. Double beds come as standard. The hotel invites guests to relax on its sun terrace, in the sauna, or with a massage. Those looking to stay in shape can head to the on-site gym for a workout. The hotel offers bed and breakfast, half- and full-board and all-inclusive stays. Breakfast is available from a buffet, whilst midday and evening meals can be selected from a set menu. À la carte dishes are available in the evening.
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Facilities Show/hide
- Hotel services
- 24 Hour Reception , 24 Hour Room Service
- In room facilities
- Safety Deposit Box
- Other
- Lift to all floors , Public Air Conditioning
- Dining
- Breakfast to go
Useful Info Show/hide
- From 14:00 hours
- Until 11:00 hours
- The price shown is based on the occupancy and dates you have searched for. Prices and availability are subject to change based on the arrival date, number of nights and occupancy searched for. All prices are inclusive of all local taxes.
- Pets are not allowed
Customer Reviews
Our reviews are from genuine LateRooms.com customers. We verify that the customer has stayed before leaving a review.
100% would recommend it to a friend
Customer service
Food quality
Room quality
Skaritz Hotel and Residence
Lovely grand hotel - but boutique - very central to town.
Great room which was very quiet even though facing front street.
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Lovely hotel
Had a lovely few days in this hotel which was very well situated within the old town.
Room was extremely large and spotlessly clean. Great value for money and would recommend!
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